1. Field of the Invention
The present general inventive concept relates to a method and apparatus to detect a dead pixel of an image sensor and a method and apparatus to capture an image from an image sensor. The general inventive concept also relates to a method and apparatus to quickly and accurately detect a dead pixel in an image sensor on a production line, and also after production and shipment, and a method and apparatus to capture an image from an image sensor.
2. Description of the Related Art
Generally, image-capturing devices such as digital cameras include image sensors capturing images using the properties of a semiconductor that reacts to light.
Each pixel of an image sensor converts light, which is incident through an optical system, into an electrical signal (e.g., a voltage signal) which varies according to the intensity of the incident light. Accordingly, images can be formed in units of pixels.
For various reasons, defective pixels are often generated in the process of manufacturing image sensors. These pixels cannot properly react to light, and an image sensor having such abnormal pixels may output a distorted image. The pixels that cannot properly react to light often appear brighter or darker than intended. Of these pixels, those having a brightness that is noticeably different from that of their neighboring pixels are conventionally referred to as “dead pixels”.
The number of dead pixels in an image sensor determines the quality or class of the image sensor. That is, the smaller the number of dead pixels, the better the quality of the image sensor. Errors caused by dead pixels are represented in the form of small dots or lines on a screen. If all image sensor chips having such partial errors are determined to be unacceptable chips, the production yield of the image sensors may be reduced.
In order to prevent the decrease in production yield, rather than disposing of image sensors having such dead pixels, detected dead pixels of image sensors may be corrected.
However, a conventional process of detecting dead pixels is performed within a screen or using a sheet of test patterns. However, many normal pixels are often recognized as dead pixels with this conventional process.
To enhance the quality control, many test patterns may be used to detect all dead pixels. However, this process is not desirable in terms of time and cost.
In addition, special equipment or a special production process is required to detect dead pixels using a sheet or several sheets of test patterns, and thus far there is no method that can be used to detect dead pixels that may become defective after the original detection process.